Duct joining systems are well known in the art and generally are utilized to join together the ends of adjacent duct sections such as heating and air conditioning ducts or the like. Such systems typically include couplers respectively fastened to the end edges of each of the walls forming the duct. In a general sense, each of the couplers is defined by an elongated channel adjacent each corner and an L-shaped corner connector with each leg coupled to one of the elongated channels adjacent each corner. When two of the L-shaped corner connectors, and thus the duct ends, are brought together in an abutting relationship, they can be attached together thus attaching the ends of the ducts together. Representative patents illustrating such type of construction include U.S. Pat. No. 4,636,105, Johansson, issued Jan. 13, 1987, U.S. Pat. No. 4,558,892, Daw et. al., issued Dec. 17, 1985, U.S. Pat. No. 4,542,923, La Crosse et. al., issued Sept. 24, 1985 and U.S. Pat. No. 3,199,901, Jeppsson, issued Aug. 10, 1965.
Each of these patented systems has disadvantages in the effectiveness of the coupling, the cost of manufacture, the cost of installation, or the difficulty in installation. When it is time consuming to install the L-shaped connectors, the cost of a project increases. Thus, it is important to provide a system for interconnecting ducts that comprises elements for an effective connection that are economical and simple to manufacture, and that are easily and quickly installed.
The present system provides a new and unique L-shaped corner connector design that permits the connectors to be easily and quickly locked to each other, obviating the use of a bolt or other type of separate fastener, although the design permits the use of a bolt if desired. Each of the L-shaped connectors has an orifice in the corner formed by the legs of the connector. A cleat is integrally formed with and extends inwardly from the peripheral edge of the orifice. When one of the corner connectors is reversed in position and placed in superimposed abutting relationship with a second connector, the cleats are on opposing peripheral edges of the orifices thus allowing each cleat to be forced through the adjacent orifice and bent over a raised flange or other retaining means on the edge of the adjacent orifice to lock the two connectors together.
A score line is formed at the base of each cleat on the outside surface of the connector to allow the cleat to be easily bent outwardly about the score line to extend through, and over the peripheral edge of, the orifice of the abutting L-shaped connector to lock the connectors together. Each cleat has a lip on the outer end thereof and a corresponding raised flange on the edge of the aligned orifice in the abutting connector for receiving the lip when the cleat is bent outwardly to extend through, and over the edge of, the abutting connector orifice to lock the lip over the raised flange or other locking means. In the preferred embodiment, the cleat extends inwardly from the periphery of each orifice in either direction along an axis perpendicular to a line extending from the inner corner of the L-shaped connector to the outer corner of the L-shaped connector.
In a second embodiment, the cleat extends inwardly from the periphery of each orifice in either direction along the longitudinal center line of either of the legs forming the L-shaped connector. In both of the embodiments previously mentioned, all L-shaped connectors are identically constructed and serve as both of the abutting L-shaped connectors placed back to back.
However, in the third embodiment, the cleat is integrally formed with, and extends inwardly from, the periphery of the orifice in only one of the connectors in either direction along a line extending from the inner corner to the outer corner of the L-shaped connector. This connector requires a left connector and a right connector. With the cleat lying along the line indicated, when the connector is rotated to place it in abutting relationship with another connector, the cleats on each of the connectors lie in the same plane. Thus only one of the connectors can have a cleat and there must be a left connector and a right connector.
The novel construction allows for the use of a bolt in addition to the locking features of the connector. A surface on which the bolt head or nut may rest is formed by raised flanges on the sides of the orifice surrounding the cleat on the inside surface of the connector. Each of the flanges are located substantially 90.degree. from each other and provide surfaces for a bolt head and nut when a bolt is extended through the aligned orifices to provide means to hold the connector and ducts together. Raised flanges are important because some of the bolts that are used in these systems are not completely threaded. Thus, as they are tightened, if the connector begins to collapse, the bolt threads may be entirely used before the connectors are completely together. With the raised flanges providing a surface for the bolt, it is difficult for the bolt to move the raised flanges inwardly thus maintaining the connector shape while the bolt is being tightened.
The legs of each of the L-shaped connector are flat metal strips having the edges thereof turned toward the inside surface to provide stiffening ribs and aid in attachment to the duct piece when used with either a picture-frame type connecting system or an integrally rolled flange connecting system, both systems being well-known in the art.
Thus, it is an object of the present invention to provide a duct joining system that is effective in achieving an improved coupling in a quick fashion when the duct ends are joined together.
It is also an object of the invention to provide a duct joining system in which no special pins are required to join the duct ends.
It is yet another object of the invention to provide a method of joining duct ends with the use of connectors that lock together in a simple manner.
It is still another object of the present invention to provide an improved L-shaped connector for use in joining the ends of ducts.